An organic light emitting device is composed of two opposing electrodes and multilayered organic material thin films having semiconductor-like properties interposed therebetween. The organic light emitting device having the configuration uses a phenomenon in which electric energy is converted into light energy by using an organic material, that is, an organic light emitting phenomenon. Specifically, when voltage is applied between two electrodes in a structure in which an organic material layer is disposed between an anode and a cathode, holes from the anode and electrons from the cathode are injected into the organic material layer. When the injected holes and electrons meet each other, an exciton is formed, and the exciton falls down again to a bottom state to emit light.
In the aforementioned organic light emitting device, the light generated from the organic material layer is emitted through a light transmissive electrode, and the organic light emitting device may be typically classified into a top emission type, a bottom emission type, and a dual emission type. In the case of the top emission or bottom emission type, one of two electrodes needs to be a light transmissive electrode, and in the case of the dual emission type, both the two electrodes need to be a light transmissive electrode.
In respect to the aforementioned organic light emitting device, many studies have been concentrated since Kodak Co., Ltd., announced that when a multilayer structure is used, the device may be driven at low voltage, and recently, a natural color display using the organic light emitting device is attached to a mobile phone and commercialized.
Further, as recent studies on the organic light emitting device using a phosphorescent material instead of an existing fluorescent material have been conducted, efficiency has been rapidly improved, and it is also expected that the device would be able to replace an existing illumination in the near future.